I. Field of the Invention
In well drilling, with a rotary drilling rig, the drill bit and drilling pipe receive rotary motion from power equipment located on the surface. Below the drilling floor, at the ground surface, an assembly known as a rotating head allows the circulation of various fluids used in the drilling. The present invention relates to a dual rubber cartridge for rotating heads for oil and gas wells and more particularly, to an improved rotating head that enables the ease of use for the end user and also a more efficient method of assembly and disassembly to decrease down time caused by assembling or disassembling the rotating head and to decrease manufacturing costs. A conventional drilling string is inserted or “stabbed” through the rotating head assembly, including the one or two rubbers rotatably mounted in the rotating head assembly, to seal the drilling string.
In well drilling, with a rotary drilling rig, the drill bit and drilling pipe receive rotary motion from power equipment located on the surface. Below the drilling floor, at the ground surface, there is usually an assembly known as a rotating head that allows the circulation of various fluids used in the drilling. Early drilling heads employed a single rubber to divert the flow of drilling fluid away from the rig floor. The rubber was fixedly mounted within the drilling head and the drill string rotated and moved longitudinally through the rubber as the rubber sealed against the string. The action of the drill string caused considerable wear on the rubber requiring frequent replacement. To reduce the abrasive wear, the rubber was rotated with the drill string to maintain sealing contact. However, a drill string typically includes various diameter sections. For example, the drill collars joining sections of drill string have a greater diameter than the drill pipe itself. Thus, the rubber was sized to maintain sealing contact with the drill pipe or the smallest diameter component which traveled through the drilling head. Because of the different diameters of the drill string, the rubber needed to be rigid enough to withstand the pressures of the drilling fluid yet resilient enough to maintain a seal on the drill collars as the drill collars passed through the drilling head and thereafter return to the original configuration to seal against the smaller diameter drill pipe. The operating cycle of the rubber was directly proportional to the number of drill collars which passed through the single rubber since the rubber would not return to its original sealing diameter.
Present day drilling operations are extremely expensive, and an effort to increase the overall efficiency of the drilling operation while minimizing expense requires the essentially continuous operation of the drilling rig. Thus, it is imperative that downtime be minimized.
In this regard, there is a need for improved sealing of the rotating head with the rubbers to maximize the useful life of the bearings. Seals for such bearings must effectively preclude the intrusion of well fluids or debris while at the same time ensuring retention of the bearing lubricant.
Primary features of the rotating head assembly of the present invention includes a dual rubber cartridge that rotatably attaches two rubbers to the drilling head such that the two rubbers rotate with the drill pipe to eliminate excess wear on the two rubbers. Further, the dual rubber cartridge of the present invention simplifies the process of removing and replacing the rubbers. The dual rubber cartridge of the present invention provides simple removal such that a user can easily replace the rubbers of the dual rubber cartridge. Further, the present invention seals the rotating head to prevent debris from entering the rotating head and prevents components from interfering with the drilling operation.
II. Description of the Known Art
Among the patents which relate to rotating head assemblies are the following:
U.S. Pat. No: 4,511,193 (the '193 patent) issued to Geczy on Apr. 16, 1985 teaches a combined radial and thrust bearing assembly for a down-hole drilling assembly to journal a shaft, mounting the drill bit, in a housing. The bearing assembly is used between a down-hole fluid powered motor and a drill bit for drilling oil wells, for example. The bearing assembly includes cooperative pairs of upper and lower inner races located on the shaft for mutual rotation. Each of the inner races includes a pair of interchangeable toroidal tracks. Cooperative pairs of upper and lower outer races are fixed against rotation in the housing. Each outer race has a pair of interchangeable toroidal tracks to selectively cooperate with the tracks of the inner races to define a toroidal channel to receive a number of bearing balls. Spring means are disposed between the upper and lower pairs of outer races and the housing and between the upper and lower pairs of outer races to provide a compliant coupling for the even distribution of radial and upwardly and downwardly directed thrust loads between the races and balls and eventual transfer to the housing. Drilling fluid is circulated through the bearing assembly for cooling and lubrication.
U.S. Pat. No. 5,213,158 (“the '158 patent”) issued to Bailey, et al. on May 25, 1993 teaches a drilling head with dual rotating stripper rubbers designed for high pressure drilling operations ensuring sealing under the extreme conditions of high flow or high pressure wells such as horizontal drilling. The dual stripper rubbers taught by the '158 patent seal on the same diameter yet are manufactured of different materials for different sealing functions. The lower stripper rubber is manufactured from a more rigid, abrasive resistant material to divert the flow from the well. The upper stripper rubber is manufactured of a softer sealing material that will closely conform to the outer diameter of the drill string thereby preventing the flow of fluids through the drilling head.
U.S. Pat. No. 5,647,444 issued to Williams on Jul. 15, 1997 discloses a rotating blowout preventor having at least two rotating stripper rubber seals which provide a continuous seal about a drilling string having drilling string components of varying diameter. A stationary bowl is designed to support a blowout preventor bearing assembly and receives a swivel ball that cooperates with the bowl to self-align the blowout preventor bearing assembly and the swivel ball with respect to the fixed bowl. Chilled water is circulated through the seal boxes of the blowout preventor bearing assembly and liquid such as water is pumped into the bearing assembly annulus between the stripper rubbers to offset well pressure on the stripper rubbers.